Nuummite is a rare metamorphic rock primarily composed of anthophyllite and gedrite amphiboles. It is highly prized by collectors for its distinctive iridescent flashes of gold, blue, or red, which are best visible when the material is polished.
Is this nuummite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch nuummite with a known reference. Nuummite sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
- 2Read the textureLook at a fresh break with a hand lens. Texture: Exsolution lamellae give iridescence; polished pieces show yellow sulfide bands.
- 3Pick out the mineralsComposition: Gedrite and anthophyllite amphiboles, with pyrite, pyrrhotite and chalcopyrite. Identify the two or three most abundant grains.
- 4Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 5Match the color rangeCompare against the expected color range: black, dark gray.
Often confused with
Nuummite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads submetallic on Nuummite and vitreous on Arfvedsonite.
How to tell apart: Luster reads submetallic on Nuummite and vitreous, pearly on cleavage on Anthophyllite.
How to tell apart: Luster reads submetallic on Nuummite and vitreous to silky on Hypersthene.
Often found alongside nuummite
Minerals reported to co-occur with nuummite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 5.5-6
- Density
- 3.1-3.3 g/cm³
- Luster
- Submetallic
- Transparency
- Opaque
- Rarity
- Uncommon
- Uses
- Lapidary, Ornamental, Collector
- Host rock
- metamorphic amphibolite complex
- Texture
- Exsolution lamellae give iridescence; polished pieces show yellow sulfide bands
- Composition
- Gedrite and anthophyllite amphiboles, with pyrite, pyrrhotite and chalcopyrite
Where rockhounds find nuummite
Classic worldwide localities
- Nuuk, Greenland
Field-hunting tip
Where it forms: metamorphic amphibolite complex. If you start seeing gedrite, anthophyllite, pyrite in float, you are in the right ground.
Common questions
How do you identify nuummite?+
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What rocks look like nuummite?+
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Find nuummite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
